28.3 and 28.4 Relativity

Relativity and the Speed of Light

An introduction to relativity followed by a discussion on how it is that the speed of light remains constant no matter what your frame of reference. Duration: 10:21.

Principle of Equivalence

Is gravity truly a force, or is it what we experience when mass has the effect of warping both space and time? Duration: 6:40.

Gravitational Time Dilation

The effect that acceleration and mass have on the passage of time is explored. Duration: 8:32.

Special Relativity

Uniform motion can only be measured relative to some external reference. This is discussed followed by three space-traveling thought experiments. Duration: 10:20.